use a pre-built commit message for when no user specified message exists

app/assets/javascripts/ide/components/commit_sidebar/form.vue

@@ -24,7 +24,7 @@ export default {
     ...mapState(['changedFiles', 'stagedFiles', 'currentActivityView', 'lastCommitMsg']),
     ...mapState('commit', ['commitMessage', 'submitCommitLoading']),
     ...mapGetters(['hasChanges']),
-    ...mapGetters('commit', ['discardDraftButtonDisabled']),
+    ...mapGetters('commit', ['discardDraftButtonDisabled', 'preBuiltCommitMessage']),
     overviewText() {
       return sprintf(
         __(
@@ -139,6 +139,7 @@ export default {
         </transition>
         <commit-message-field
           :text="commitMessage"
+          :placeholder="preBuiltCommitMessage"
           @input="updateCommitMessage"
         />
         <div class="clearfix prepend-top-15">

app/assets/javascripts/ide/components/commit_sidebar/message_field.vue

@@ -16,6 +16,10 @@ export default {
       type: String,
       required: true,
     },
+    placeholder: {
+      type: String,
+      required: true,
+    },
   },
   data() {
     return {
@@ -114,7 +118,7 @@ export default {
         </div>
         <textarea
           ref="textarea"
-          :placeholder="__('Write a commit message...')"
+          :placeholder="placeholder"
           :value="text"
           class="note-textarea ide-commit-message-textarea"
           name="commit-message"

app/assets/javascripts/ide/stores/modules/commit/actions.js

@@ -103,12 +103,6 @@ export const updateFilesAfterCommit = ({ commit, dispatch, rootState }, { data }
 
 export const commitChanges = ({ commit, state, getters, dispatch, rootState, rootGetters }) => {
   const newBranch = state.commitAction !== consts.COMMIT_TO_CURRENT_BRANCH;
-  const payload = createCommitPayload({
-    branch: getters.branchName,
-    newBranch,
-    state,
-    rootState,
-  });
   const stageFilesPromise = rootState.stagedFiles.length
     ? Promise.resolve()
     : dispatch('stageAllChanges', null, { root: true });
@@ -116,7 +110,17 @@ export const commitChanges = ({ commit, state, getters, dispatch, rootState, roo
   commit(types.UPDATE_LOADING, true);
 
   return stageFilesPromise
-    .then(() => service.commit(rootState.currentProjectId, payload))
+    .then(() => {
+      const payload = createCommitPayload({
+        branch: getters.branchName,
+        newBranch,
+        getters,
+        state,
+        rootState,
+      });
+
+      return service.commit(rootState.currentProjectId, payload);
+    })
     .then(({ data }) => {
       commit(types.UPDATE_LOADING, false);
 

app/assets/javascripts/ide/stores/modules/commit/getters.js

+import { sprintf, n__ } from '../../../../locale';
 import * as consts from './constants';
 
 const BRANCH_SUFFIX_COUNT = 5;
@@ -25,5 +26,18 @@ export const branchName = (state, getters, rootState) => {
   return rootState.currentBranchId;
 };
 
+export const preBuiltCommitMessage = (state, _, rootState) => {
+  if (state.commitMessage) return state.commitMessage;
+
+  const files = (rootState.stagedFiles.length
+    ? rootState.stagedFiles
+    : rootState.changedFiles
+  ).reduce((acc, val) => acc.concat(val.path), []);
+
+  return sprintf(n__('Update %{files}', 'Update %{files} files', files.length), {
+    files: files.join(', '),
+  });
+};
+
 // prevent babel-plugin-rewire from generating an invalid default during karma tests
 export default () => {};

app/assets/javascripts/ide/stores/utils.js

@@ -105,9 +105,9 @@ export const setPageTitle = title => {
   document.title = title;
 };
 
-export const createCommitPayload = ({ branch, newBranch, state, rootState }) => ({
+export const createCommitPayload = ({ branch, getters, newBranch, state, rootState }) => ({
   branch,
-  commit_message: state.commitMessage,
+  commit_message: state.commitMessage || getters.preBuiltCommitMessage,
   actions: rootState.stagedFiles.map(f => ({
     action: f.tempFile ? 'create' : 'update',
     file_path: f.path,